This invention finds specific application in the field of treating agricultural grain products such as soybean, corn or cereal grains which can be described as particulate material. However, the invention has application in other fields for processing of other types of particulate material, although the invention will be described with respect to the processing of agricultural grain products to demonstrate its unique capabilities in enhancing the treatment process.
One type of processing of agricultural grain products consists of heating of the grain to effect roasting and thus effect changes in the state or condition of the grain. One such apparatus for effecting roasting of the grain comprises a treatment chamber which includes a horizontally disposed bottom plate over which the grain is caused to traverse with that plate being perforated to permit passage of treatment media such as heated air to pass therethrough and then through the layer of grain. Transfer of the grain over that plate is effected by a drag conveyor of elongated construction such that the lower run will cause the grain to move at a predetermined rate in accordance with the treatment media being passed through the grain such that the grain will be fully processed during its travel from an inlet through a discharge end of the treatment chamber.
It is important that the introduction of the unprocessed grain be effected in a manner such that the heated air or other treatment media will not escape from the treatment chamber through the inlet or entrance end to that chamber. It is also important that the grain be introduced at a controlled flow rate to form a layer of uniform depth on a supporting bedplate in order to optimize the effect of the processing or treatment. This is necessary as such apparatus is set up and adjusted to operate at a predetermined constant condition as to the amount of material that can be processed during its traversing of the treatment chamber in accordance with the conditions and characteristics of the treatment media. A drag conveyor such as is utilized in the specific grain roasting apparatus utilized as an example of such mechanisms requires introduction of particulate material comprises a number of flights formed by transversely extending sheets or plates that are longitudinally spaced a distance to accommodate a specified amount of the material and to effect its displacement over the bedplate. Feeding apparatus that has been utilized in association with such treatment apparatus has included dispensing mechanisms of the paddle wheel type as well as the auger type conveyors. A paddle-type dispenser comprises a number of elongated blades that are angularly spaced about a central supporting axle and extend radially outward from that axle. This paddle assembly is disposed in an elongated tubular housing having an inlet aperture formed at an upper side through which the material flows into the housing by gravity. As the paddle mechanism is revolved, quantities of the material are then entrapped between adjacent blades or paddles and revolve to a downward position associated with a discharge opening. At that point, the material entrapped between a pair of blades is then dropped or dumped through the discharge opening and onto the conveyor and supporting bedplate. While a paddle-type dispenser is capable of providing a substantially satisfactory air lock to prevent loss of the treatment media such as heated air through the inlet, the disadvantage of such a mechanism is that the material is not deposited in a uniform layer. The material is deposited in a pulse-type action in batches that are determined by the size of the paddles and their relative spacing. Control over the rate of inflow is accomplished by altering the rotational speed of the paddles in accordance with the rate of movement effected by the drag conveyor. Since the drag conveyor is operated at a speed such that the material will be maintained in the processing chamber for a predetermined time interval, it is thus necessary that the paddle-type dispenser be provided with a variable speed drive so that it may be adjusted to accommodate the speed of the drag conveyor and to also deposit the particulate material in a layer of desired thickness for a specific processing operation. This requires relatively expensive drive motors and mechanisms as well as associated complex control equipment. The auger-type conveyors suffer the same operational disadvantage of requiring variable speed drives for the same reasons as the paddle-type dispenser, but, additionally, auger-type conveyors do not provide a good air lock to prevent outflow of the treatment media through the infeeding mechanism.
Another disadvantage of the paddle-type feed mechanism is that uniformity of the quantity of material and the consequent thickness of the layer between two adjacent conveyor flights cannot be reliably controlled. The paddles of such a dispenser deliver the product in discreet quantities and it is not possible to assure that those quantities are delivered totally to a single space between adjacent flights. It is very likely that the paddle delivery system will not be synchronized with the movement of the conveyor flights, and thus, quantities or batches of the material may be delivered at the passage of a conveyor flight and be split as between two adjacent spaces in a manner that cannot be predicted to divide a batch evenly or equally between the two adjacent conveyor flight spaces.